Hi All!

I have to go through quite a big line operating network which contsists of 2x S7-300 and 2x S7-400 PLC's. Unfortunatley I am not quite fammiliar with Profibus networks. 

I was reading through manuals and some samples and I'd like to ask for assistance in understanding some issues. If some of my assumtions are wrong, please correct me.

1. For 2 PLC's to be able to operate in FDL network, both units must have Profibus CP cards, PB ports on CPU won't go?

2. I managed to set Profibus DP connection on my test unit S7-400 and S7-300 PLC's (414-3 & 315-2 DP) where PB allows to control I an Q over the network between both units. I'd like to, however, transmitt data set in DB's (like status, speed, temperature, other more complex information), simply copy and overwrite them from machine's PLC;s to line "master" PLC. Can I do it by Profibus DP? Or how can I do it if I dont have CP cards on CPU's?

3. It is my understanding that if one CPU with CP card has called FC5 with certain ID, other FC6 with the same ID, this is all that defines connection (of course NetPro card LADDR config must be set too)?

4. What does FDL acronym stand for anyway?

 Hello vulpes;

Let's go through your questionss one by one:

1) Yes. See the following document:

FDL communication with SDA service via PROFIBUS CPs and Send/Receive interface

2) You could, by copying the data from your DB to input/output addresses, but it is time consuming and a bit clunky. You can use S7 communication blocks such as BSEND/BRCV (lient-server exchanges) between your 2 CPUs over a Profibus-DP connection, on the CPU or on a CP.

See this link:

How do you program communication blocks FB12 "BSEND" and FB13 "BRCV" for data exchange in the S7 program of an S7-300 CPU?

BSEND/BRCV can exchange up to 64 kB between 2 DBs (one on each CPU), if you need that much power. Look at the extract from the CPU-CPU communications compendium below.

Take the following notice into account when programming the FBs in your PLCs, the location of the libraries is different for the S7-300 blocks and the S7-400 blocks:

Note about S7 communication:
The S7-300 supports S7 communication via the FB14/15 "GET/PUT", FB12/13 "BSEND/BRCV" or FB8/9 "USEND/URCV" function blocks.It works via:

• the integrated PN interface with the function blocks from the Standard Library -> Communication Blocks.
• CPs with the function blocks from the SIMATIC_NET_CP library.

In the S7-400, data exchange takes place via the SFB14/15 "GET/PUT", SFB12/13 "BSEND/BRCV" or SFB8/9 "USEND/URCV" function blocks. They can be found in the Standard Library -> System Function Block

Which types of connection/protocols do the S7-300/400 CPUs and the CPs support by default?

3) Yes.

4) Fieldbus Data Link, see the first link proposed earlier.

Hope this helps,

Daniel Chartier

Hi! Thank You for anwser.

Few quick questions :

1. If DB nr on PLC that sends data is i.e. 20, must DB nr on recieve side be 20 as well?

2. I read through the document and I will make some tests, but do I have to move data from source memory to target area? BLKMOV I checked the program for the machine that I have and I see it simply points to DB which is also used by another FC, that changes values in there. 

3. Can I use AG_RECV with different ID's to collect data to one DB. For example I have one line "main" PLC with DB20 that is a structure of data intended to be collected as a status of lines each component. Each component has PLC that gatheres data in its own DB20 (lets say each line has three bytes of data). Now each component sends AG_SEND ID=1/2/3 and "main" PLC collects it:

AG_ERCV ID:=1 RECV:=DB20.DBX0.0 BYTE 3

AG_ERCV ID:=2 RECV:=DB20.DBX3.0 BYTE 3

AG_ERCV ID:=3 RECV:=DB20.DBX6.0 BYTE 3

?